Effect of Reglan (Metoclopramide) on Small Bowel Motility
Yes, Reglan (metoclopramide) does stimulate small intestinal transit and increases peristalsis of the duodenum and jejunum, resulting in accelerated intestinal transit. 1
Mechanism of Action and Effects on Small Bowel
- Metoclopramide acts as a D2 dopamine receptor antagonist that stimulates gastric emptying and small intestinal transit 2
- It increases the release of acetylcholine from enteric nerves, enhancing gastrointestinal motility 1
- The drug increases peristalsis specifically in the duodenum and jejunum, accelerating small bowel transit time 1, 3
- Its prokinetic effects begin within 30-60 minutes following oral administration and persist for 1-2 hours 1
Clinical Applications Related to Small Bowel Motility
- Metoclopramide may be used in conditions requiring increased small intestinal motility, such as diabetic gastroparesis 1, 4
- It can be beneficial in certain cases of small intestinal dysmotility, though evidence for consistent benefit in gastroparesis is limited 2
- The drug is sometimes used to facilitate intubation of the small intestine and passage of barium into the intestine for radiographic procedures 4
Limitations and Cautions
- The European Medicines Agency's Committee recommends against long-term use of metoclopramide due to risk of extrapyramidal side effects and potentially irreversible tardive dyskinesia, especially in elderly patients 2
- Metoclopramide has little to no effect on colonic motility or gallbladder function 1
- It should be used with caution after bowel anastomosis as prokinetic drugs are generally not recommended in this setting 2
- In a study examining gastric residence time (GRT) and mouth-to-cecum transit time (MCTT), metoclopramide showed inconsistent effects on MCTT despite affecting GRT 5
Alternative Prokinetic Agents for Small Bowel Motility
- Erythromycin (a motilin agonist) may be more effective for small bowel dysmotility, particularly in cases with absent or impaired antroduodenal migrating complexes 2
- Azithromycin has been suggested as potentially more effective than erythromycin for small bowel dysmotility 2
- Prucalopride, a selective 5-HT4 receptor agonist, has been used for constipation and appears to have fewer cardiac risks than older agents like cisapride 2
- Octreotide (a somatostatin analogue) may be beneficial in cases of small intestinal dysmotility, especially when other treatments have failed 2
Metoclopramide's effects on small bowel motility make it a useful agent in specific clinical scenarios, but its use must be balanced against potential side effects, particularly with long-term administration.